The construction industry commonly uses modified bitumen membranes or single ply membranes to provide a waterproof barrier on flat or low-slope roofs. An insulation or protective layer formed from construction boards is often provided over the roof deck and under the membranes. The most common construction boards are made of polyisocyanurate, also referred to as iso boards, and may be coated with a protective facer that can be either rigid or flexible and can be fire or flame retardant. The construction boards provide thermal insulation and a uniform surface over which the membranes are installed.
Construction boards are conventionally secured to the roof deck by fasteners passing through the construction board and into the roof deck. A fastening plate, also referred to as an insulation plate, is often provided on a top surface of the construction board, and includes a hole through which the fastener is received. The fastening plate provides a larger surface area of contact with the top surface of the construction board to improve the wind uplift resistance of the construction board. Fastening plates are available commercially in a wide variety of forms, but are often circular in shape and may have a diameter of approximately 3 inches. The fastening plates may include ribs or other strengthening devices to improve the rigidity of the fastening plate.
Due to the wind uplift forces experienced on many roof surfaces, it is often necessary to provide a large number of fastening plates and fasteners to adequately secure the construction board to the roof deck. For example, a construction board that is 4 feet by 4 feet may require as many as 16 fastening plates and fasteners to adequately secure it to a roof deck. Similarly, a construction board that is 8 feet by 4 feet may require as many as 32 fastening plates and fasteners to adequately secure it to a roof deck. The wind uplift resistance of a construction board secured with fastening plates and fasteners is also dependent upon the location and spacing of the fastening plates during installation. Thus, weak areas that are susceptible to failure may be created during installation if roofing technicians do not correctly locate and space the fastening plates and fasteners in the construction board. When a weak point is created, and one fastening plate fails, additional stress is placed upon adjacent fastening plates, and failure of the entire roofing assembly then becomes more likely.
Thus, there is a need for an improved fastening plate assembly that provides better wind uplift resistance of a construction board.